FI81372C - Liquid coating composition which can be cured at ambient temperature - Google Patents

Abstract

The invention provides a liquid coating composition curable at ambient temperature based on an alpha , beta -ethylenically unsaturated carbonyl compound and a particular compound with an activated CH group such as a malonic oligomer or polymer.

Description

1 81372

Ambient temperature curable liquid coating composition

The invention relates to a liquid coating composition based on a compound containing an activated CH group and a carbonyl compound containing a C 1-4 ethylene double bond.

A coating composition of the above-mentioned type is known, inter alia, from DE-A-835 809. It proposes acetoacetates, acetoacetamides and cyanoacetates as compounds containing an activated CH group. Examples of suitable carbonyl compounds containing a β, β-ethylene double bond are acrylic and methacrylic acid esters and amides. In practice, however, it has been found that these known compositions are generally not capable of curing sufficiently at room temperature, and therefore special measures must be taken to heat an article coated with such a composition to the desired elevated temperature. This is a disadvantage, especially in the case of large steel structures, for example.

It should be noted that the polyamine-curable epoxy resin-based coating composition can also be cured at room temperature; however, the gloss retention of the resulting pavements is insufficient when the pavements are exposed to the outside air. In addition, compositions based on a polyisocyanate and a suitable hydroxyl compound also cure at room temperature, although polyisocyanates may be harmful to health and may therefore only be used when certain special precautions are taken.

This invention relates to compositions which can be used without special precautions and which can be cured very well at ambient or even lower temperatures and which result in coatings having advantageous properties such as gloss retention, hardness and flexibility.

2,81372

The coating composition according to the invention is characterized in that the compound containing an activated CH group is a compound of the formula R, OC-CHR 1 -CO - R.-O-C-CHR -.-C-O - - R 0 0 LO 0 - <n 5 wherein R 1, R 2 and R 2 are independently selected organic radicals derived from a hydrocarbon, polyurethane, oligomeric ester or polyester, polyether, epoxy resin, poly (meth) acrylate, poly-10 polyamide or polyvinyl resin having at least one hydroxy or epoxy group, R 1 is hydrogen, an R 4 group or a group of the formula -CH 2 -CHR 4 -COOR 4, in which R 1 is C 1 -C 4 alkyl and R 1 is hydrogen or methyl and n is at least 1; and having a molecular weight of 250 to 50,000. The compound containing an activated CH group according to the invention is hereinafter referred to as a malonate compound.

Examples of suitable oligomeric or polymeric malonate compounds include polyurethanes, polyesters, polyacrylates, epoxy resins, polyamides, and polyvinyl resins containing either main or side chain or both malonate groups.

Suitable malonate-containing polyurethanes can be obtained, for example, by reacting a polyisocyanate with a hydroxyl-containing ester of a polyol and malonic acid, esterifying a hydroxy-functional polyurethane with malonic acid, or carrying out a transesterification of a hydroxy-functional polyurethane with a dialkyl malonate. Examples of suitable polyisocyanates are hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate and addition products between polyol and diisocyanate, such as trimethylolpropane ethylene isopropylate, hexane methylene or isophorone diisocyanate, iso-cyanurates obtained and 3 molecular diisocyanates such as hexamethylene diisocyanate, and 1 molecular water

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3 81 372 biurets. Examples of suitable hydroxy-functional polyurethanes are polyisocyanate and polyol polyol products of polyolocyanates, polyether polyols, polyether polyols, polyether polyols, polyethylene polyols, polyethylene polyols, polyethylene polyols,

Suitable malonic acid polyesters can be obtained, for example, by polycondensation of malonic acid, an alkylmalonic acid such as ethylmalonic acid, a mono-10 or dialkyl ester of such a carboxylic acid or a reaction product of a malonic acid ester with an alkyl (meth) acrylate or a multihydroxy or with a compound containing hydroxyl functional groups, optionally mixed with monofunctional hydroxyl and / or carboxylic acid compounds. Examples of suitable polyhydroxy compounds include compounds having 2 to 6 hydroxyl groups and 2 to 20 carbon atoms, such as ethylene glycol, diethylene glycol, propylene glycol, tri-20-methylethane, trimethylolpropane, glycerol, pentaerythritol and sorbitol.

Suitable polymers containing malonate groups can also be prepared by transesterifying an excess of dialkyl malonate with a hydroxy-functional polymer such as a vinyl alcohol styrene copolymer. In this way, polymers are formed which contain malonate groups in the side chains. After the reaction, the excess dialkyl malonate can optionally be either removed under reduced pressure and used as a reactive solvent.

Suitable epoxy esters of malonic acid can be prepared by esterifying an epoxy resin with malonic acid or a monoester of malonic acid or by transesterifying it using dialkyl malonate in the presence of one or more other carboxylic acids or carboxylic acid derivatives, optionally.

Suitable polyamides can be obtained in the same manner as 4,831,372 polyesters by replacing at least some of the hydroxyl compound (s) with a monovalent or polyvalent primary and / or secondary amine such as cyclohexylamine, ethylenediamine, isophoronediamine, hexaminediamine or hexenethylene methylene. The reactions discussed above are well known to those skilled in the art and need not be described in more detail here.

Preferred malonate compounds to be used are oligomeric esters containing malonate groups, polyesters, polyurethanes and epoxy resins containing 2 to 100, preferably 2 to 20, malonate groups per molecule. The number average molecular weight of the malonate compounds should preferably be 250 to 30,000 and the acid number not more than 5, preferably not more than 2. Malonate compounds in which the Malo-15 nitric acid moiety is cyclized with formaldehyde, acetaldehyde, acetone or cyclohexanone can be used if desired.

The carbonyl compound containing a γ-ethylene double bond to be used as the second component can generally be any ethylenically unsaturated compound whose carbon-carbon double bond is activated by a carbonyl group in the β-position. An example of a typical group of compounds is acrylic or methacrylic acid esters formed by hydroxyl compounds having 1 to 6 OH groups and 1 to 20 carbon atoms. Esters may contain hydroxyl groups. Examples of suitable esters are hexanediol diacrylate, trimethylolpropane triacrylate and Penta-erythritol triacrylate. Instead of or in addition to (meth) acrylic acid, for example, crotonic acid or cinnamic acid can be used. As another example of the group of compounds, mention may be made of polyesters based on maleic acid or maleic anhydride, fumaric acid and / or itaconic acid and a divalent or polyvalent hydroxyl compound and optionally a monovalent hydroxyl and / or carboxylic compound. Other suitable groups of compounds are polyester resins containing acrylic acid groups and / or methacrylic acid groups

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5 81 372 or alkyd resins. Examples of other suitable compounds are urethane (meth) acrylates obtained by reacting a polyisocyanate with a (meth) acrylic acid ester containing a free hydroxyl group prepared, for example, by esterifying a polyhydroxy compound with a less than a stoichiometric amount of (meth) acrylic; polyether (meth) acrylates obtained by esterification of a polyether containing hydroxyl groups with (meth) acrylic acid; polyfunctional (meth) acrylates obtained by reacting a hydroxy-10-alkyl (meth) acrylate with a dicarboxylic acid, a compound containing glycidyl groups or an amino resin; poly (meth) acrylates obtained by reacting (meth) acrylic acid or (meth) acrylic anhydride with an epoxy resin; and products obtained by reacting polycaprolacto-15 nidiol or polyol with a polyisocyanate and hydroxyalkyl (meth) acrylate. All of these types of compounds are familiar to those skilled in the art and need not be described in more detail herein. Preferably, a polyol ester containing an acrylic acid group or methacrylic acid groups, a polyurethane, a polyacrylate or an amino resin containing 2 to 10 functional groups and having an acid number of at most 1 should be used.

The above two components are reacted with each other according to a so-called Michael addition mechanism, in which the malonate anion of the first component is attached to one of the carbon atoms forming the ethylene double bond of the second component. The composition contains the two components in such a ratio that the ratio of the number of malonate groups of the first component to the number of carbon-carbon double bonds of the second component is 1 / 4-4, preferably 1 / 2-2.

Although separate malonate compounds and carbonyl compounds containing a β-ethylene double bond are discussed above, the invention also allows the use of compounds containing both a malonate group and a carbonyl moiety containing a β, γ-ethylene double bond in the same molecule.

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The illustrative compound can be prepared, for example, by treating a hydroxyl-containing malonic acid polyester with, for example, a diisocyanate whose isocyanate group has already reacted with a hydroxyalkyl (meth) acrylate. For example, the polyester 5 can be reacted with an adduct formed by reacting 1 mole of isophorone diisocyanate with 1 mole of hydroxyethyl acrylate. The amounts of starting materials selected are quite crucial for the malonate groups and the ethylenically unsaturated carbonyl-10 units.

The coating composition preferably also contains a catalyst for the reaction between the two components or units mentioned above. Suitable catalysts include electrically neutral bases such as amines and their derivatives. Preferably, a base having an acid-base pair acid having a pKa of at least 12 should be used, such as amidine-type amines, examples of which are tetramethylguanidine, 1,4-dihydropyrimidines, 1,8-diaza / 5.4.07bicycloundecene and 2-alkyl-N-alkyl -20 imidazoline. Amines such as triethylamine, dibutylamine and 1,4-diaza / 2.2.27-bicyclooctane do not catalyze the crosslinking reaction unless the temperature is raised to about 150 ° C. Another suitable group of electrically neutral bases includes base metals such as lithium, sodium and potassium. Electrically charged bases are also suitable catalysts according to the invention, provided that the pKa of the acid formed by the acid-base pair conjugated with the base in question is 5-45, preferably 9-19. Examples of typical bases include metal bases and quaternary ammonium bases. Examples of suitable bases include metal oxides such as sodium methanate; metal hydroxides such as potassium hydroxide; metal phenoxides such as sodium phenolate; metal-hydrocarbon compounds such as n-butyllithium; metal hydrides such as sodium hydride; metal amides such as potassium amide; metal carbonates such as potassium carbonate; quaternary ammonium hydroxide

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7,831,372 binders such as tetrabutylanonium hydroxide; quaternary ammonium alkoxides such as benzyltrimethylammonium methoxide; and quaternary ammonium carbanions such as benzyl trimethylammonium acetyl acetate.

The catalyst is generally included in the composition in an amount of 0.1 to 10 equivalent percent, preferably 0.5 to 5 equivalent percent, for each malonate equivalent.

If desired, the activity of the catalyst can be slowed or reduced by mixing it with an additive proton solvent having a pKa of 5-14, preferably 9-11, such as acetylacetone, acetylbutyrolactone, ethylacetoacetate or dimethylmalonate.

The coating composition may optionally and depending on the area of use contain one or more pigments, colorants and conventional fillers, additives and solvents. Examples of suitable inert organic solvents include ketones, esters and aromatic and aliphatic hydrocarbons; examples of suitable reactive organic solvents include dimethyl malonate, diethyl malonate and (2-ethylhexyl) acrylate.

The coating composition may be applied to the substrate by any suitable means, for example by brushing, spraying, spraying or dipping. Suitable substrates include, for example, metal, wood, paper and leather substrates, as well as substrates made of synthetic material. The curing of the applied coating can be carried out in a very suitable manner, for example at a temperature of 0-30 ° C. It is possible to use a temperature higher than 30 ° C, which can shorten the curing time.

Preparation of Malonate Resins A. A mixture of 495 parts by weight of 1,6-hexane diol, 503 parts by weight of dimethyl malonate and 2 parts by weight of dibutyltin oxide was heated in a reaction vessel under a stream of nitrogen while stirring at 105 ° C and 35 ° C. further to 200 ° C. After the addition of 20 parts by weight of hexane, the remaining methanol was removed tropical 81372. The temperature was then lowered to 160 ° C, and 167 parts by weight of xylene were added to the resulting resin, resulting in a 79.4% by weight resin solution having a viscosity of 65 cPa.s. The malonate-5 resin A prepared had an acid number of 0.1, a hydroxyl number of 62, a number average molecular weight of 2450 and an equivalent weight of 250 based on the resin solution.

B. A mixture of 392 parts by weight of dimethylcyclohexane, 110 parts by weight of trimethylolpropane, 297 parts by weight of dimethyl malonate, 199 parts by weight of dimethylhexahydrotherephthalate and 2 parts by weight of dibutyltin oxide was heated in a reaction vessel under a stream of 200 ° C with nitrogen while stirring. C temperature. After 2 hours, 90 mL of hexane was added slowly and the remaining methanol was removed azeotropically. Finally, the polycondensation mixture was distilled under reduced pressure at 200 ° C. After cooling, 339 parts by weight of xylene were added to the prepared resin, resulting in a 69.0% by weight resin solution having a viscosity of 210 cPa.s. The 20 malonate resin B prepared had an acid number of 0.23, a hydroxyl number of 110, a number average molecular weight of 2150 and an equivalent weight of 503 based on the resin solution.

C. A mixture of 330 parts by weight of dimethyl malonate, 470 parts by weight of dimethylolyclohexane, 35 parts by weight of 25 trimethylolpropane, 2 parts by weight of dibutyltin oxide and 33 parts by weight of xylene was heated in a reaction vessel under a stream of nitrogen while stirring at 200 ° C: n temperature. After 2 hours, 55 parts by weight of xylene were slowly added, and the remaining methanol was distilled off in two to 30 hours. After cooling, 173 parts by weight of 2-acetoxy-1-methoxypropane were added. Then, 163 parts by weight of isophorone diisocyanate dissolved in 173 parts by weight of xylene were added to the mixture over 1 hour at 80 ° C, followed by reaction for 1 hour at 100 ° C. After cooling, a 66% by weight resin solution having a viscosity of 450 cPa.s. The resulting malonate resin C had an acid number of n 81 81 372, a hydroxyl number of 65, a number average molecular weight of 2800 and an equivalent weight of 506 based on the resin solution.

D. A mixture of 194 parts by weight of dimethylolyclo-5-hexane, 173 parts by weight of isophthalic acid, 109 parts by weight of trimethylolpropane, 2 parts by weight of dibutyltin oxide and 27 parts by weight of xylene was heated in a reaction vessel under nitrogen with stirring at 200 ° C: n temperature. After 2 hours, the mixture was cooled to 100 ° C and 10,229 parts by weight of isophoronediamine and 329 parts by weight of dimethyl malonate were added, and the mixture was heated to 200 ° C. After two hours, 56 parts by weight of xylene were slowly added, and the remaining methanol was distilled off in two hours. After cooling and subsequent addition of xylene 15 (234 parts by weight) and 2-acetoxy-1-methoxypropane (234 parts by weight), a 60% by weight resin solution having a viscosity of 510 cPa.s. The malonate resin D prepared had an acid number of 0.56, a hydroxyl number of 85, a number average molecular weight of 1500 and an equivalent weight of 20,540 based on the resin solution.

Example 1 A coating composition was prepared by successively mixing 10 parts by weight of malonate resin A solution, 2 parts by weight of n-butanol, 0.2 parts by weight of a 40% by weight benzyl 25 trimethylammonium methoxide solution and 4.2 parts by weight of trimethylolpropane. The resulting composition was applied to a steel plate (Bonder No 120) so that the thickness of the coating became 60 μm (after drying), after which the plate was kept at 20 ° C. After 7 to 30 seasons, the Persoz hardness of the coating was 40 seconds. The gelling time of the obtained composition was 5 minutes.

Example 2 The coating composition was prepared by successively mixing 7.2 parts by weight of malonate resin A solution, 0.15 parts by weight to 35 parts by weight of a 40% by weight solution of benzyltrimethylammonium methoxide in methanol and 19 parts by weight of the addition product obtained from 1 mol of product. isocyanate and 2 moles of hydroxypropyl acrylate. The resulting composition was applied to a steel plate (Bonder No. 120) so that the thickness of the coating became 60 μm (after drying); After 2 hours at 18 ° C, the coating had sufficiently cured (Persoz hardness 70 seconds) and was resistant to solvents such as xylene and methyl ethyl ketone. The gelling time of the resulting composition was 8 minutes.

Example 3 A coating composition was prepared by successively mixing 0.5 part by weight of acetylacetone, 4.5 part by weight of xylene, 0.1 part by weight of a 40% by weight solution of benzyltrimethylammonium methoxide in methanol, 15.9 parts by weight of malonate resin. solution and 3.0 parts by weight of trimethylol-15 propane triacrylate. The resulting composition with a gel time of 30 hours was applied to a steel plate (Bonder 120) so that the coating became 60 μm thick (after drying); after 7 days at 20 ° C, the coating had sufficiently cured (Persoz hardness 80 seconds) and was resistant to xylene and methyl ethyl ketone.

Example 4

Example 3 was repeated with the exception that acetylacetone and benzyltrimethylammonium methoxide were jointly replaced with 0.22 parts by weight of tetramethylguanidine. The composition, which had a gel time of 1 hour, resulted in a coating with similar properties.

Example 5

Example 4 was repeated with the exception that tetramethylguanidine was replaced with either 0.16 parts by weight of 1,4-diaza / 2.2.27-bicycloisooctane (DABCO) or 0.16 parts by weight of dibutylamine. The prepared compositions had a gelling time of more than 3 months and at 180 ° C gave sufficient cured coatings to withstand methyl ethyl ketone.

Il n 81372

Example 6 The coating composition was prepared by successively mixing 0.6 parts by weight of acetylacetone, 0.22 parts by weight of 40% by weight benzyltrimethylammonium methoxide in methanol, 4.9 parts by weight of xylene, 20.0 parts by weight of resin solution C and 5.1 parts by weight of trimethylolpropane triacrylate. The resulting composition was stable for 2 hours and was applied to a steel plate (Bonder 120) so that the coating thickness became 60 μm (after drying); after 10 days the coating was kept at 20 ° C for 7 days, it had hardened sufficiently (Persoz hardness for 70 seconds) and was resistant to xylene and methyl ethyl ketone.

Example 7

Example 6 was repeated with the exception that the trimethylolpropane triacrylate was replaced with 9.0 parts by weight of a solution containing 75% of the adduct obtained from 1 mole of isophorone diisocyanate and 2 moles of pentaerythritol triacrylate. The coating composition was stable for 4 hours and was applied to a steel plate (Bonder 120) so that the thickness of the coating was 60 [mu] m (after drying); after keeping the coating at 7 ° C for 7 days, the coating had hardened sufficiently (Persoz hardness for 200 seconds) and was resistant to xylene and methyl ethyl ketone.

Claims (12)

12 81 372 A liquid coating composition based on a compound containing an activated CH group and an α, β-ethylenically unsaturated carbonyl compound, characterized in that the compound containing an activated CH group is a compound of the formula 10 R. O-C-CHR, -C-O - -R, O-C-CHR, -C-O - -R, 1 l 3 II 4 II 3 II 2 and R 4 are independently selected organic radicals derived from a hydrocarbon, polyurethane, oligomeric ester or polyester, polyether, epoxy resin, poly (meth) acrylate, polyamide or polyvinyl resin having at least one hydroxy or epoxy group, R 3 is hydrogen , An R 5-20 group or a group of the formula -CH 2 -CHR 6 -C 20 R 5, wherein R 5 represents C 1 -C 18 alkyl and R 6 represents hydrogen or methyl and n is at least 1; and having a compound having a molecular weight of 250 to 50,000. Coating composition according to Claim 1, characterized in that the compound containing an activated CH group is an oligomeric or polymeric malonate compound. Coating composition according to Claim 2, characterized in that the malonate compound is a polyurethane, polyester, polyacrylate, epoxy resin, polyamide or polyvinyl resin which contains malonate groups in the main and / or side chain. Coating composition according to Claim 1, characterized in that the compound containing the activated CH group 35 is an oligomeric ester, polyester, polymethane or epoxy ester containing malonate groups and containing from 2 to 100 malonate groups per molecule. Coating composition according to Claim 1, characterized in that the compound having an activated CH group 5 has a number-average molecular weight of 250 to 30,000 and an acid number of at most 5. Coating composition according to any one of Claims 1 to 5, characterized in that it also contains a catalyst for the reaction between a compound containing an activated CH group and an α, β-ethylenically unsaturated carbonyl compound. Coating composition according to Claim 6, characterized in that the catalyst is an electrically neutral base, the conjugated acid forming an acid-base pair with the base having a pKa of at least 12. Coating composition according to Claim 6, characterized in that the catalyst is an electrically charged base, the conjugated acid forming an acid-base pair with the base having a pKa of 5 to 45. Coating composition according to any one of Claims 6 to 8, characterized in that it contains 0.1 to 10 equivalent% of catalyst per equivalent of compound containing activated 25 CH group. m 81372